In recent years, there are mobile terminals such as mobile phones that employ input apparatuses having touch sensors such as touch panels, touch switches, or the like, as input apparatuses such as operation units, switches and the like configured to receive input operations by users. Such input apparatuses having touch sensors are popularly employed not only by the mobile terminals but also by information equipments such as calculators, ticket vending machines, home electric appliances such as microwaves, TV sets, lighting equipments, industrial equipments (FA equipments) and the like.
There are known a variety of types of those touch sensors, such as a resistive film type, a capacitive type, an optical type and the like. However, touch sensors of any of these types receive a touch input by a finger or a stylus pen, and, unlike push-button switches, touch sensors themselves are not physically displaced when touched.
Since the touch sensors themselves are not physically displaced when touched, an operator cannot obtain feedback to an input even though the touch input is received. As an operation feeling to “have pressed or have canceled pressing down” is not obtained in operation input, the operator cannot perceive whether the touch sensor detects the operation input. As a result, the operator is likely to repeat inputting the same spot multiple times, which may be stressful for the operator.
In order to prevent such unnecessary repetitive inputs, there are known input apparatuses allowing for visual or auditory confirmation of the input operations by, for example, generating sounds when detecting the touch input or by changing a display state, such as colors of input objects such as input buttons and the like graphically depicted on a display unit, based on an input position.
However, such auditory feedback may be difficult to be confirmed in a noisy environment and is not applicable when the equipment being used is in a silent mode. In addition, in using such visual feedback, if the input object displayed on the display unit is small, the operator may not be able to confirm the change in the display state, as a view of the input object is blocked by a finger, particularly when the operator is inputting by the finger.
In order to deal with such a problem, there is also suggested a feedback method relying on neither the auditory- nor visual sensation but instead generating a tactile sensation at operator's fingertip by vibrating the touch sensor when the touch sensor detects an input (for example, see Patent Documents 1, 2).